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RE: Brick Veneer Spray-on water repellant

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Rich,

 

Water repellant may be appropriate if you can exclude all moisture from the wall.  If not, the water repellant may reduce that walls ability to breathe and the repellant may tend to trap moisture inside the surface, eventually resulting in exfoliation of the masonry surface.

 

If wind-driven rain can fall against the wall and wet it, and the building is very tightly sealed against changes in atmospheric pressure, an interesting & troublesome phenomenon can take place.  Constant atmospheric pressure inside the building can be alternately higher and lower than the outside pressure.  When the pressure on the outside is higher than on the inside, it can force water into the wall through cracks and “bug” holes in the mortar, even by-passing the repellant.  In the project I’m remembering, weep holes at the base of the wall that would have helped equalize the pressure had been plugged by insect nests.

 

Nels Roselund, SE

South San Gabriel, CA

njineer(--nospam--at)att.net


From: Rich Lewis [mailto:seaint03(--nospam--at)lewisengineering.com]
Sent: Monday, August 01, 2005 9:51 AM
To: seaint(--nospam--at)seaint.org
Subject: Brick Veneer Spray-on water repellant

 

I am looking at a 25 year old building that has a brick veneer and metal stud backup.  The veneer has started to have water penetration this year into the building in one area.  It only occurs when the wind is blowing the rain in the direction of the wall.  When it blows the opposite direction the wall does not appear to leak.  The owner has already applied some water repellant to the surface.  I don’t know the brand yet.  I need to find it out.  It still leaks some even after this initial application.  They have now called me in to help with the solution to the problem.  I would like some suggestion for products for a spray on water repellent for brick veneer.  What have others found to work best?  I’m not necessarily looking for a brand name product (although I will take one) as I am the material.  Should it be a silicone, a silane, or something else?  Should it be an absorption type material that is soaked in end then repells water, like a silane, or one that coats the surface more?

 

Appreciate any insight.

 

Rich